Introducer assembly and methods of use

ABSTRACT

A method and apparatus for inserting at least a portion of a sensor into a patient is provided. Simple and easy to use mechanisms are provided that can position the sensor or any other device accurately with minimal complication. The method and apparatus can include an inserter device for use with the sensor. The method and apparatus can be for use in continuous or semi-continuous monitoring systems such as analyte monitoring systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/663,016, filed Mar. 19, 2015, which is a continuation ofU.S. patent application Ser. No. 11/380,883, filed Apr. 28, 2006, nowabandoned, the disclosures of both of which are incorporated herein byreference in their entireties for all purposes.

BACKGROUND

Analyte monitoring systems generally include a sensor such as asubcutaneous analyte sensor, at least a portion of which is insertedunder the skin for fluid contact with interstitial fluid, for detectinganalyte levels such as glucose levels, a transmitter (such as an RFtransmitter) in communication with the sensor and configured to receivethe sensor signals and to transmit them to a corresponding receiver unitby for example, using RF data transmission protocol. The receiver may beoperatively coupled to a glucose monitor that performs glucose relatedcalculations and data analysis.

The transmitter is in signal communication with the sensor. Generally,the sensor is configured to detect and measure the glucose levels of thepatient over a predetermined period of time, and the transmitter isconfigured to transmit data corresponding to or associated with themeasured glucose levels over the predetermined period of time forfurther analysis. To initially deploy the sensor so that the sensorcontacts and electrodes are in fluid contact with the patient's analytefluids, a separate deployment mechanism such as a sensor inserter orintroducer is used. More specifically, the introducer includes a sharpneedle shaped inserter that is configured to pierce through the skin ofthe patient and substantially concurrently guide the sensor through thepatient's skin so as to place at least a portion of the sensor in fluidcontact with the target biological fluid of the patient.

The inserter is typically used only during the sensor insertion process,and once the sensor is properly and accurately positioned, the inserterand the introducer are discarded. This requires a level of care as theinserter is sharp and may damage other parts of the patient's skin ifnot properly handled. Further, since the tip of the inserter has comeinto fluid contact with the patient's biological fluids, it is importantto take particular precautions in the handling of the inserter.

Further, to minimize data errors in the continuous or semi-continuousmonitoring system, it is important to properly insert the sensor throughthe patient's skin and securely retain the sensor during the time thatthe sensor is configured to detect analyte levels. Additionally, for theperiod of continuous or semi-continuous monitoring which can include,for example, 3 days, 5 days or 7 days, it is important to have thetransmitter in proper signal contact with the analyte sensor so as tominimize the potential errors in the monitored data.

In view of the foregoing, it would be desirable to have method andapparatus for providing simple, easy to handle and accurate sensorintroduction and retention mechanism for use in an analyte monitoringsystem. More specifically, it would be desirable to have method andapparatus that minimizes the number of components which the patient hasto handle, and which also reduces the number of required steps toproperly and accurately position the analyte sensor in fluid contactwith the patient's analytes.

SUMMARY

In one embodiment, there is provided a method and apparatus forproviding an a sensor introduction and retention mechanism for use incontinuous or semi-continuous monitoring systems such as analytemonitoring systems which includes a sensor loaded insertion device whichis configured to align and correspondingly mate with a base sectiondisposed on the patient's skin (such as for example, a transmitter mountunit provided on an adhesive patch that is attached or otherwise fixedlypositioned on the desired location on the patient's skin).

In one embodiment of the present invention, the base section is providedwith a receiving structure that is configured to align with acorresponding section of the insertion device so as to accuratelyposition the sensor relative to the patient's skin for proper insertionthrough the skin of the patient. In one aspect, the activation of thepre-loaded trigger mechanism by the patient displaces the sensor in theinsertion device from the insertion device and places at least a portionof the sensor in fluid contact with the patient's analytes. Upon sensordeployment, the insertion device may be removed from the base sectionand discarded (in case of disposable insertion devices), while the basesection may be configured to retain the sensor in proper position untilthe transmitter unit is mounted or coupled to the base section so as tobe in signal contact with the deployed sensor.

These and other features and advantages of the present invention will beunderstood upon consideration of the following detailed description ofthe invention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of the overall assembly for sensorinsertion and positioning system in accordance with one embodiment ofthe present invention;

FIG. 2A illustrates a perspective view of the insertion device for usein the sensor insertion and positioning system in accordance with oneembodiment of the present invention;

FIG. 2B illustrates a perspective view of the plunger coupled with thesensor and sensor introducer of the insertion device shown in FIG. 2A inone embodiment of the present invention;

FIG. 2C illustrates a perspective view of the analyte sensor for use inthe sensor insertion and positioning system in accordance with oneembodiment of the present invention;

FIG. 2D illustrates an adhesive patch with a receiving structure of theinsertion and positioning system in accordance with one embodiment ofthe present invention;

FIG. 3A illustrates a side cross sectional view of the plunger movementduring the sensor insertion process in the sensor insertion andpositioning system in accordance with one embodiment of the presentinvention;

FIG. 3B illustrates a side cross sectional view of the plungersubstantially at the final position for placement of the sensor in thesensor insertion and positioning system in accordance with oneembodiment of the present invention;

FIG. 3C illustrates a side cross sectional view of the plunger of theinsertion device in retracted position during the insertion deviceremoval process in the sensor insertion and positioning system inaccordance with one embodiment of the present invention;

FIG. 3D is a cross sectional perspective view of the plunger of theinsertion device in retracted position during the insertion deviceremoval process shown in FIG. 3C in accordance with one embodiment ofthe present invention;

FIG. 4A illustrates a side perspective view of the sensor positioned inthe patient and the insertion device removed from the receivingstructure in the sensor insertion and positioning system in accordancewith one embodiment of the present invention;

FIG. 4B illustrates a cross sectional perspective view of the sensorpositioned and secured to the retaining pin on the adhesive patch asshown in FIG. 4A in accordance with one embodiment of the presentinvention;

FIG. 4C illustrates a side cross sectional view of the sensor positionedand secured to the retaining pin on the adhesive patch shown in FIG. 4Bin accordance with one embodiment of the present invention; and

FIG. 5 illustrates a perspective view of the transmitter unit mounted onthe adhesive patch for signal communication with the sensor in thesensor insertion and positioning system in accordance with oneembodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates a perspective view of the overall assembly for sensorinsertion and positioning system in accordance with one embodiment ofthe present invention. Referring to FIG. 1, the sensor insertion andpositioning system 100 in one embodiment of the present inventionincludes an insertion device comprising, for example, a plunger handleportion 101 and a plunger body portion 102, and coupled therewith anintroducer such as a sharp or a needle (not shown) and a sensor (notshown). The insertion device further includes a sleeve portion 103 whichis configured to mate with a receiving structure 104 disposed on anadhesive layer 105. The adhesive layer 105 is configured to be fixedlypositioned on the skin of a patient, and further, where the receivingstructure 104 in one embodiment is positioned on a predeterminedposition on the adhesive layer 105.

Referring to FIG. 1, in one embodiment of the present invention, thehandle portion of the plunger 101, the body portion 102 of the plunger102, the sensor and introducer provided substantially within the bodyportion 102 of the plunger and the sleeve 103 are provided as a singleintegrated insertion device for use by patients, for example. Theadhesive layer 105 with the receiving structure 104 are further providedin one embodiment as a separate integrated device such that the patientmay in one embodiment, position the adhesive layer 105 at a desiredlocation on the patient's skin, with relative ease, and where theposition of the receiving structure 104 disposed on the adhesive layer105 substantially defines the position where the sensor is to be placedin the patient.

Referring again to FIG. 1, as discussed in further detail below, thereceiving structure 104 in one embodiment of the present invention isconfigured to align the insertion device (for example, the sleeveportion 103 of the insertion device so as to accurately position thesensor and the sensor introducer prior to the insertion process. Thatis, the sleeve portion 103 of the insertion device is configured tosubstantially mate or securely latch with the receiving structure 104such that, upon placement of a predefined length of the sleeve portion103 in the receiving structure 104, the insertion device is securelypositioned with the sensor and the introducer aligned for propersubcutaneous placement in the patient.

In this manner, in one embodiment of the present invention, the patientmay easily and with relative simple process, accurately position thesensor for placement under the skin layer. Moreover, in one embodiment,the insertion device is configured to predefine the depth of insertionof the introducer and sensor. As discussed in further detail below, inone embodiment of the present invention, after positioning the sleeveportion 103 of the insertion device so as to be aligned with thereceiving structure 104, the patient applies pressure upon the handleportion 101 of the insertion device which in turn displaces the bodyportion 102 of the insertion device (which also correspondingly movesthe sensor and the introducer provided therein).

When the body portion 102 of the insertion device has traveled apredetermined distance in response to the applied pressure on the handleportion 101 of the insertion device, in one embodiment, the body portion102 is configured to so that additional application of pressure on thehandle portion 101 of the insertion device will not displace the bodyportion 102 (and thus the introducer and the sensor). Accordingly, inone embodiment, the patient may conveniently and accurately position thesensor to a desired and/or predetermined depth under the skin, and thussubstantially remove significant variation in the sensor insertiondepth.

Referring back to FIG. 1, in one embodiment of the present invention,when the patient removes the applied pressure on the handle portion 101of the insertion device (for example, after fully driving the sensor andintroducer to the predetermined depth under the skin layer), aretraction mechanism (not shown) within the insertion device may beconfigured to automatically withdraw the body portion 102 (as well asthe introducer coupled to the body portion) of the insertion device suchthat the positioned sensor is retained in place while the introducer isremoved from the patient. Referring yet again to FIG. 1, upon retractionof the introducer from the patient, the insertion device may be removedfrom the receiving structure 104 and discarded.

Referring yet again to FIG. 1, as discussed in further detail inconjunction with FIG. 5, upon removal of the insertion device, atransmitter unit may be positioned on the adhesive layer 105 such thatthe electrical contacts on the transmitter unit are in signalcommunication with the electrodes of the sensor, and where the sensor isin fluid communication with the patient's analytes.

Referring still again to FIG. 1, the insertion device may be providedwith a spring loaded retraction mechanism with forward biasing, suchthat, when the patient applies pressure on the handle portion 101, thebody portion (including the introducer and the sensor) are drivensubstantially towards the patient's skin to pierce the desired locationon the skin so that the sensor and the introducer are placed at apredetermined depth under the skin layer. Thereafter, by simply removingthe applied pressure on the handle portion 101 of the insertion device,the body portion 102 and the coupled introducer are removed orretracted.

In the manner described above, accordance with the various embodimentsof the present invention, there are provided simple and easy to usemechanism to position the sensor or any other device accurately withminimal complication. Moreover, with the forward biasing mechanism inthe insertion device for automatically retracting the introducer aftersensor position, among other features, within the scope of the presentinvention, the patient may position the sensor and mount the transmitterunit using one hand. Moreover, the receiving structure 104 provided onthe adhesive layer 105 in one embodiment provides simple insertionprocess without significant visual aid—that is, a patient is able toposition the sensor by simply aligning the insertion device with thereceiving structure 104 and drive the handle portion 102 of theinsertion device to accurately position the sensor, remove theintroducer, and subsequently couple the transmitter unit so as to be insignal communication with the sensor.

In addition, by reducing the number of components needed for sensorplacement, within the scope of the present invention, other benefitssuch as reduction in material cost, weight, packaging, and associatedhandling and disposal may be achieved.

FIG. 2A illustrates a perspective view of the insertion device for usein the sensor insertion and positioning system in accordance with oneembodiment of the present invention. Referring to FIG. 2A, in oneembodiment of the present invention, the body portion 102 of theinsertion device as shown is configured to slidably move relative to thesleeve portion to displace introducer 201 coupled to the body portion102 of the insertion device.

FIG. 2B illustrates a perspective view of the plunger coupled with thesensor and sensor introducer of the insertion device shown in FIG. 2A inone embodiment of the present invention. Referring to FIG. 2B, it can beseen that the introducer 201 is positioned and aligned such that thesensor comprising the insertion section 202B, is configured to move withthe movement of the introducer 201. In addition, as can be seen, in oneembodiment, the contact section 202A of the sensor is positionedsubstantially within the body portion 102 of the insertion device.

Moreover, referring again to FIG. 2B, the contact section 202A of thesensor is provided with an engagement element 202C such as a hole whichis configured to correspondingly mate with a retainer element (notshown) provided on the receiving structure 104. Accordingly, upon finalpositioning of the sensor, the engagement element 202C in one embodimentis configured to engage the retainer element so that the sensor may besubstantially fixedly positioned to minimize potential error orundesirable displacement when the transmitter unit is mounted on theadhesive layer 105 to establish electrical contact with the sensorelectrodes.

FIG. 2C illustrates a perspective view of the analyte sensor for use inthe sensor insertion and positioning system in accordance with oneembodiment of the present invention. As can be seen, in one embodiment,the sensor is provided with a contact section 202A which issubstantially retained outside of the patient's body, while theinsertion section 202B is configured to be substantially positionedunder the skin layer of the patient so as to be in fluid contact withthe patient's analytes for monitoring. The sensor electrodes areconfigured to be in signal communication with the corresponding contactpoints on the transmitter unit for each of the working, counter andreference electrode of the sensor. Moreover, the engagement element 202Cas shown in FIG. 2C is configured to retain the sensor substantially inthe inserted position upon deployment by, for example, engaging with theretainer element disposed on the receiving structure 104 (FIG. 1) on theadhesive layer 105.

While a circular engagement element 202C and a substantially circularcontact section 202A of the sensor are shown in the Figures, within thescope of the present invention, the engagement element 202C and thecontact section 202A of the sensor may comprise any other shapes.

FIG. 2D illustrates an adhesive patch with a receiving structure of theinsertion and positioning system in accordance with one embodiment ofthe present invention. As shown in FIG. 2D, the receiving structure 104is configured to receive the sleeve portion 103 of the insertion deviceso as to substantially fixedly retain the insertion device in positionduring the sensor placement and introducer removal process. For example,in one embodiment, the receiving structure 104 may be biased with alatch mechanism such that when the sleeve portion 103 of the insertiondevice is cooperatingly aligned and coupled to with the receivingstructure 104, the receiving structure may be configured to fixedlyretain the sleeve portion 103 of the insertion device with thepre-configured biasing force to retain the walls of the insertion devicein position, and thereafter, to release the sleeve portion 103 of theinsertion device when the patient pull the insertion device away fromthe receiving structure 104 after sensor deployment and introducerrefraction.

FIG. 3A illustrates a side cross sectional view of the plunger movementduring the sensor insertion process in the sensor insertion andpositioning system in accordance with one embodiment of the presentinvention. In particular, referring to FIG. 3A, the retainer element 301is shown. As can be seen from the Figure, as the sensor and theintroducer 201 is driven through the skin layer of the patient, theengagement element 202C of the sensor contacts the retainer element 301.In one embodiment, the retainer element 301 is configured with apredefined groove or indentation substantially around the outer surfacethereof, which is configured to retain the engagement element 202C in asubstantially fixed position relative to the retainer element 301.

Referring back to FIG. 3A, while a tapered structure is shown in theFigure for the retainer element 301, within the scope of the presentinvention, the retainer element 301 may include, for example, a barb, aminiature rivet, a hook, a button snap, a combination thereof, or anyother equivalent alternatives. Similarly, the sensor engagement element202C within the scope of the present invention may include a hole of anyshape. In addition, the sensor engagement element 202C may, within thescope of the present invention, include a button snap, a socket, a lockwasher, a combination thereof, or any other equivalent shape orstructure to correspondingly mate with retainer element 301.

FIG. 3B illustrates a side cross sectional view of the plungersubstantially at the final position for placement of the sensor in thesensor insertion and positioning system in accordance with oneembodiment of the present invention, while FIG. 3C illustrates a sidecross sectional view of the plunger of the insertion device in retractedposition during the insertion device removal process in the sensorinsertion and positioning system in accordance with one embodiment ofthe present invention.

More specifically, in FIG. 3B, the patient has applied sufficientpressure on the handle portion 101 of the insertion device to positionthe sensor and the introducer 201 at the desired position under the skinlayer, and in FIG. 3C, upon release of the applied pressure on thehandle portion 101 of the insertion device, the body portion 102 of theinsertion device is refracted while removing the introducer 201 with theretraction of the body portion 102 of the insertion device. As shown inFIG. 3C, when the introducer 201 is removed, the insertion section 202Bof the sensor is retained in position under the skin layer.

FIG. 3D a cross sectional perspective view of the plunger of theinsertion device in retracted position during the insertion deviceremoval process shown in FIG. 3C in accordance with one embodiment ofthe present invention. Referring to FIG. 3D, it can be seen that theengagement element 202C of the sensor is coupled to the retainer element301 so as to substantially fixedly position the sensor post insertionprocess.

FIG. 4A illustrates a side perspective view of the sensor positioned inthe patient and the insertion device removed from the receivingstructure, FIG. 4B illustrates a cross sectional perspective view of thesensor positioned and secured to the retaining pin on the adhesive patchas shown in FIG. 4A, and FIG. 4C illustrates a side cross sectional viewof the sensor positioned and secured to the retaining pin on theadhesive patch shown in FIG. 4B in accordance with one embodiment of thepresent invention.

FIG. 5 illustrates a perspective view of the transmitter unit mounted onthe adhesive patch for signal communication with the sensor in thesensor insertion and positioning system in accordance with oneembodiment of the present invention. Referring to FIG. 5, transmitterunit 501 in one embodiment is configured to be coupled to the sensor soas to be in electrical contact with the sensor electrodes which are influid contact with the patient's analytes. Upon deployment, thetransmitter unit 501 is configured in one embodiment to be securelypositioned on the adhesive layer, and in signal communication with thesensor.

In this manner, in one embodiment, the sensor detected analyte levelsare provided to the transmitter unit 501, for example, as currentsignals, and which are in turn, converted to respective digital signalsfor transmission (including, for example, RF transmission) to a receiverunit for further data processing and data analysis (including drug(e.g., insulin) therapy management, infusion control, and healthmonitoring and treatment, for example). That is, the monitored analytedata may be used by the patient and/or the patient's healthcare providerto modify the patient's therapy such as an infusion protocol (such asbasal profile modifications in the case of diabetics) as necessary toimprove insulin infusion therapy for diabetics, and further, to analyzetrends in analyte levels for better treatment.

While glucose is described as an example of the detected and/ormonitored analyte, within the scope of the present invention, analytesthat may be detected or monitored also include, for example, acetylcholine, amylase, bilirubin, cholesterol, chorionic gonadotropin,creatine kinase (e.g., CK-MB), creatine, DNA, fructosamine, glucose,glutamine, growth hormones, hormones, ketones, lactate, peroxide,prostate-specific antigen, prothrombin, RNA, thyroid stimulatinghormone, and troponin. The concentration of drugs, such as, for example,antibiotics (e.g., gentamicin, vancomycin, and the like), digitoxin,digoxin, drugs of abuse, theophylline, and warfarin, may also bedetected and/or monitored.

While the sensor is described as substantially transcutaneously placedin the patient, within the scope of the present invention, the sensormay be wholly implantable under the skin of the patient, or at least aportion of the sensor may be provided under the skin of the patient soas to be in fluid contact with the patient's analyte.

Referring back to FIG. 5, the detected analyte signals from the sensorare provided to transmitter unit 501, which is, in one embodiment,configured to wirelessly or otherwise transmit data corresponding to thedetected analyte levels from the sensor to a receiver unit, where thereceiver unit may include an analyte, e.g., glucose, monitor unit and/oran insulin pump unit and/or a computer terminal and/or any otherelectronic device capable of being configured for wirelesscommunication. A physical connection may be provided in certainembodiments.

Within the scope of the present invention, the receiver unit functionsmay be integrated into portable electronic devices such as a watch, apager, a mobile telephone, and a personal digital assistant. Additionalinformation on the detection, monitoring and analysis of analyte levelsare described in further detail in U.S. Pat. No. 6,175,752 entitled“Analyte Monitoring Device and Methods of Use”. In certain embodiments,the transmitter may also be capable of wirelessly or otherwise receivingsignal from a receiver such that a receiver may also be capable oftransmitting information to the transmitter.

In a further embodiment, the transmitter unit 501 may include a wirelesscommunication unit for wireless transmission of the signal, where thewireless communication unit may include one or more of a radio frequency(RF) communication unit, a Bluetooth communication unit, an infraredcommunication unit, an 801.11x communication unit, or a Zigbeecommunication unit. Similarly, the receiver unit may be configured tosupport one more or of the above-referenced wireless communicationprotocols to communicate with the transmitter unit.

Accordingly, an introducer system in accordance with one embodiment ofthe present invention includes an insertion device, and a base sectionincluding a receiving structure configured to receive at least a portionof the insertion device, the receiving structure configured tosubstantially retain at least a portion of the insertion device at apredetermined position relative to the base section.

The base section may include an adhesive layer, where the receivingstructure may be disposed on the adhesive layer.

In one embodiment, the receiving structure may include a retentionelement configured to substantially mate with the insertion device,where the insertion device may further include a sensor and anintroducer substantially engaged with at least a portion of the sensor.Moreover, the sensor may include an engagement element, said engagementelement configured to substantially couple to the retention element.

The introducer may include a piercing member, said piercing membercoupled to at least a portion of the sensor, where the piercing memberand the at least the portion of the sensor may be configured to piercethrough a skin layer of a patient, and further, where the at least theportion of the sensor is maintained in fluid contact with an analyte ofthe patient.

The sensor may include an analyte sensor.

A method of positioning a sensor in accordance with another embodimentof the present invention includes aligning a sensor relative to aninsertion site, coupling the sensor to a receiving structure, anddeploying the sensor.

In addition, aligning may include positioning the sensor substantiallyat a predetermined angle relative to the surface of the insertion site,where the predetermined angle may include one or substantially less than90 degrees.

Also, coupling may include mating a portion of the sensor with a portionof the receiving structure.

The method may also include maintaining at least a portion of the sensorin fluid contact with an analyte of a patient. Moreover, the method mayalso include detecting one or more analyte related signals associatedwith an analyte level of the patient, and transmitting the detected oneor more analyte related signals. Also, detected one or more analyterelated signals may be wirelessly transmitted at a predeterminedtransmission rate.

The method may also include coupling an introducer to the sensor, andretracting the introducer after deploying the sensor, where theintroducer may be substantially decoupled from the sensor.

An insertion kit in accordance with a further embodiment of the presentinvention includes an insertion unit including an introducer coupled toa sensor, and a base unit substantially configured to be aligned with aportion of the introducer, the base unit configured to couple to theinsertion unit during sensor insertion, wherein the insertion unit issubstantially entirely detached from the base unit when the sensor isplaced at a predetermined position under a skin layer of a patient.

Various other modifications and alterations in the structure and methodof operation of this invention will be apparent to those skilled in theart without departing from the scope and spirit of the invention.Although the invention has been described in connection with specificpreferred embodiments, it should be understood that the invention asclaimed should not be unduly limited to such specific embodiments. It isintended that the following claims define the scope of the presentinvention and that structures and methods within the scope of theseclaims and their equivalents be covered thereby.

What is claimed is:
 1. An analyte monitoring system, comprising: areceiving structure; a sensor assembly comprising a first portion and asecond portion, the first portion having a through hole and the secondportion having a projecting retainer element in a set position withrespect to the receiving structure; and an insertion device thatcomprises a sleeve portion and a body portion movable with respect tothe sleeve portion, wherein the insertion device is coupled with thefirst portion of the sensor assembly, wherein movement of the bodyportion causes movement of the first portion of the sensor assembly, andwherein the sleeve portion is alignable with and insertable into thereceiving structure, and wherein the system is configured such thatadvancement of the body portion with respect to the sleeve portion,while the sleeve portion is inserted in the receiving structure, causesthe through hole in the first portion to pass over the projectingretainer element of the second portion and couple the first and secondportions together.
 2. The system of claim 1, wherein the projectingretainer element is a pin.
 3. The system of claim 1, wherein theprojecting retainer element has a groove or an indentation substantiallyaround an outer surface thereof.
 4. The system of claim 3, wherein thesystem is configured such that advancement of the body portion withrespect to the sleeve portion causes the through hole in the firstportion to pass over the groove or the indentation of the projectingretainer element.
 5. The system of claim 4, wherein the system isconfigured such that the first portion and the second portion of thesensor assembly are secured to each other once the through hole in thefirst portion of the sensor assembly passes over the groove orindentation of the projecting retainer element.
 6. The system of claim1, wherein the receiving structure comprises an inner wall and an outerwall.
 7. The system of claim 6, wherein the sleeve portion is insertablebetween the inner wall and the outer wall.
 8. The system of claim 1,wherein the sleeve portion is cylindrical and the receiving structurecomprises a channel.
 9. The system of claim 8, wherein the sleeveportion is insertable into the channel.
 10. The system of claim 1,wherein the projecting retainer element is at a center of the receivingstructure.
 11. The system of claim 1, wherein the receiving structureextends around the projecting retainer element.
 12. The system of claim1, wherein the receiving structure is configured to fixedly retain thesleeve portion after insertion of the sleeve portion into the receivingstructure.
 13. The system of claim 1, wherein an edge extends radiallyoutwardly from the receiving structure.
 14. The system of claim 13,wherein the system is configured such that the sleeve portion isremovable from the receiving structure after advancement of the bodyportion with respect to the sleeve portion.
 15. The system of claim 1,wherein the body portion is a plunger body portion that is coupled witha sharp introducer, and wherein the system is configured such that thesharp introducer is insertable into a patient's skin upon advancement ofthe body portion with respect to the sleeve portion.
 16. The system ofclaim 1, wherein the insertion device comprises a spring.
 17. The systemof claim 16, wherein the spring is configured to automatically remove asharp introducer from the sensor assembly.
 18. The system of claim 1,wherein a handle is coupled with the body portion, and wherein the bodyportion is advanceable with respect to the sleeve portion withoutadvancement of the handle within the sleeve portion.
 19. The system ofclaim 1, wherein the body portion comprises an interior space, andwherein the body portion is advanceable with respect to the sleeveportion such that the projecting retainer element advances into theinterior space of the body portion.